No Canadian Maps on my 1490 LMT Nuvi only lower 49.

Is your device meant to have the Canadian maps? Were they there when you bought the device? If so you should be able to select Reinstall or Change Maps on the Device tab in Express.

If you've never used Express to update your maps I believe you will first need to download what's on offer, afterwards you should see the Change region options.

Note in 'Garmin speak' the lower 49 are the 50 US states less Alaska https://buy.garmin.com/en-GB/GB/maps/on-the-road-maps/city-navigator-nt/city-navigator-north-america-nt-lower-49-states/prod28765.html

To add to what SUSSAMB said: CN NA NT 2015.10 consists of the USA, Canada, Mexico, Grand Bahama, Nassau, Grand Cayman, Jamaica, Puerto Rico, Guadeloupe, Martinique and French Guiana. The "Lower 49" is all of that minus Canada, Mexico and Alaska.

The North American version of the 1490T cannot hold all of CN NA NT 2015.10 in internal memory. You either have to put all the maps on a microSD card or split them beteen internal memory and card (as I do).

I believe from posts in the past that this is the case.

I assume you don't have the maps on your Mac. If so my advice is to use GE (I don't have a Mac and hence the Mac version to tell you how) to load the maps to your Mac ("Computer Only") and then use BC (actually MapInstall) to put the maps of Canada on your 2GB card. GE hides many advanced options quite well so I suspect you need to go through many screens to find the right one.

This FAQ explains how https://support.garmin.com/support/searchSupport/case.faces?caseId={9c806740-426f-11e2-e8a7-000000000000}

update option: lower 49 states only

I just got Garmin nuvi 50 lifetime. I have update&install "lower 49 states", which is the only option can be chosen.
but all I want is Canada. My friend told me this GPS included the map of whole North America and even some countries of South America. Anyone can help out ?

I assume you used Garmin Express to install the maps. GarminMapUpdater offers more options when selectively installing maps.

Not sure if the whole map product will fit in a nuvi 50.

Note that the nuvi 50LM came in two versions ... part # 010-00991-21 came with the lower 48 states map and was a few dollars cheaper than part # 010-00991-20 which came with US and Canada map. I suspect you have the model without Canada maps, and I doubt if Garmin will allow you to use the lifetime map subscription that came with it to expand the map coverage.

Note that the nuvi 50LM came in two versions ... part # 010-00991-21 came with the lower 48 states map and was a few dollars cheaper than part # 010-00991-20 which came with US and Canada map.

I knew Garmin did that years ago but didn't show they still did (and did with the 50LM). I learned my "fact for the day" :)

And its right in the "Version" selection at

https://buy.garmin.com/en-US/US/on-the-road/automotive/previous%20models/nuvi-50lm/prod100840.html